Ringsby & Maher (2025): Do oversimplified durability metrics undervalue biochar carbon dioxide removal?
Alexandra Jo Ringsby and Kate Maher IN: Environmental Research Letters, 2025, DOI 10.1088/1748-9326/adac7b
Quantifying CDR for biochar projects hinges critically on the durability of biochar materials once amended in soil. However, consensus on the definition of durability is still evolving, and as a result, standards developing organizations have generated a variety of different methodologies to assess the removal value of biochar projects. These methodologies primarily rely on single-parameter regression models to link the molar H/C ratio—an easily measurable bulk chemical metric—to the modeled durability of biochar materials. Specific deployment variables are not commonly considered. Thus, although H/C-based methodologies simplify project development and CDR assessment, questions remain as to how well they predict real project outcomes.